Visualization can be a useful tool. When you read a novel, you picture what is happening. Architects use it to design a building in their head. Athletes and dancers might mentally walk through routines. These are fine, good, and healthy uses of the imagination that God has given us.
There is, however, a line we should not cross. The problem comes when you use visualization in a spiritual context. That is the point where you cross over into the occult and it becomes an open door for the demonic. It is not a tool for creating anything, visualizing a conversation with “Jesus”, getting God to do something, or to create or “attract” health and wealth.